上一期談過了「Be」的語法功能，這期來看「Be+不定式動詞」這個常見結構可表示哪些語義。
「Be+不定式動詞」在不同情況下，可以表示很多種不同的語義。下面便是其中九種：
⒈表示堅決的命令。例如：
1. This naughty boy is to stay here until the class is over.
2. No one is to enter this building without the permission of the security guard.
⒉表示「計劃」或「安排的事項」。例如：
3. Betty is to be married soon.
4. An insurance agent is to meet us this afternoon.
⒊表示「可能性」。例如：
5. Are you to pay the debt for your wife?
6. The lovely puppy is nowhere to be found.
⒋表示「意圖」或「打算」。例如：
7. If you are to be there on time, you had better hurry.
8. If all of us are to remain friendly, we must be sincere with one another.
⒌表示「應該」。例如：
9. You have done so well. You are to be rewarded.
10. Such nasty questions are to be avoided.
⒍表示「不可避免」。例如：
11. Anne was wondering what was to become of her boy friend, Tommy.
12. The murderer was sentenced to life imprisonment and was never to see his family again.
⒎表示「假設」。例如：
13. If I were to do it, I would do it well.
14. Even if you were to take a taxi now, you would not be able to arrive at your destinaton on time.
⒏有「期待將來」的含意。例如：
15. The actual usefulness of the newly invented equipment is still to be determined.
16. Henry's appointment with the accountancy firm is yet to be confirmed.
⒐有「必然會發生」的含意。例如：
17. She did not think too much of her unkind acts. However, they were to be harmful to herself, too.
18. Tom wasn't worried about his head injury, but it was to be troublesome for him later.
上述九種「Be+不定式動詞」的語義，稍縱即逝，常常會不多留意，而且也不會時常用到它們，但是只要定睛注意，多少也會領略這些結構的箇中味。